Answer question

PU STATE FEEDBACK ERROR IN ACS 880

SIR I AM USING ASC880 .THE DRIVE GETS READY IN LOCAL CONTROL MODE WITH FREQUENCY CONTROL MODE. WHEN THE DRIVE IS STARTED THROUGH KEYPAD WITH 0.0 RPM REFERENCE THE DRIVE STARTS BUT WHEN THE REFERENCE IS INCREASED TO EVEN 0.1RPM THE DRIVE TRIPS IN FAULT 5696(PU STATE FEEDBACK).
THERE IS NO ENCODER CONNECTED IT IS OPEN LOOP. WHAT IS THE POSSIBLE FAULT?

THANKS,
ARINDAM